Healthy lifestyle, healthy eyes in old age

NEW YORK (Reuters Health) - People who lead overall healthy lives -- getting exercise, eating right, and not smoking -- are significantly more likely to keep their aging eyes healthy, new study findings report.

Exercise and diet were each linked to a lower risk of age-related degenerative changes in the eyes, but both combined, along with a lack of smoking, caused a "particularly profound lowering" of the risk -- by more than 70 percent, study author Dr. Julie Mares of the University of Wisconsin in Madison told Reuters Health.

"We don't need to be passive victims of these ravages of old age," Mares said. "Relatively small things could make a difference in whether or not we develop AMD (age-related macular degeneration) in our lifetime."

"Eat well, move, and don't smoke," she advised.

As the population ages, the concern over AMD grows. The disease is most common among people 75 and older, a group that will triple in size over the next 40 years, Mares noted. Already, one in four people older than 65 have early signs of AMD, she said.

AMD is caused by abnormal blood vessel growth behind the retina or a breakdown of light-sensitive cells within the retina itself, both of which can lead to serious vision impairment.

There is no cure, but a U.S. government clinical trial recently found that a high-dose mix of specific antioxidants -- vitamins C and E, beta-carotene and zinc -- can slow the progression of AMD in the intermediate stages, and doctors now commonly prescribe it for such patients.

Another study published earlier this year found that older adults who eat fatty fish at least once a week may have a lower risk of serious vision loss from AMD.

But healthy habits tend to work together in achieving certain health goals, such as lowering blood pressure, Mares noted, suggesting that diet and exercise could have a synergistic impact on eye health into old age.

To investigate, she and her colleagues reviewed information about diet, exercise, and smoking from 1,313 women between the ages of 55 and 74, collected during the 1990s. Women were revisited on average six years later, at which point they received an eye exam to check for AMD.

Two hundred and two women had AMD, most of it early-stage disease.

Among the women who ate the healthiest, 11 percent had developed an early form of AMD. In contrast, the condition was present in 19 percent of women with the worst diets, factoring in their intake of fruit, vegetables, whole grains, fat and sugar, among other elements.

About one in 10 women who exercised the most developed AMD, versus one in five of those who barely got any exercise. When the researchers combined the influence of diet, exercise and no smoking, the risk of AMD decreased even further, even though smoking alone was not related to AMD.

Since previous research has linked specific dietary elements to AMD, the researchers looked at the associations of specific antioxidants with AMD risk. Women with higher levels of these antioxidants were less likely to develop AMD, but not as much as women who ate well overall, Mares noted. "The findings for overall healthy diets are much stronger than for single nutrients," she said.

And when it comes to exercise, even women who didn't hit the gym everyday saw a benefit, the researcher added. Simply 10 hours of light exercise -- including housework, gardening, or walking -- or 8 hours of moderate exercise ("exercise you can talk to") per week was associated with a lower risk of AMD, Mares said.

The study doesn't conclusively prove that a healthy lifestyle causes the decrease in AMD, but there are many possible reasons why that might be the case, Mares said. Diet and exercise lower blood pressure, for instance, which can protect the eyes from degeneration. They also reduce the production of damaging free radicals, and are associated with lower levels of inflammation. These effects could directly protect against AMD or help enhance the accumulation of pigments at the back of the eye, which absorb potentially damaging light.

Even though the study only included women, Mares said she suspects there will be a similar trend in men. "There's no reason I can think of to expect different results in men or women. However, these findings need to be confirmed in separate samples that include men."

"Decades of studies -- basic science, retrospective and prospective clinical trials -- have all established that AMD is, in part, a nutrition-responsive disease," Dr. Stuart Richer of the Captain James Lovell Federal Health Care Facility told Reuters Health in an e-mail.

Furthermore, AMD is associated with cardiovascular health, Richer noted, suggesting that "nutritional choice, smoking cessation, and cardiovascular conditioning have myriad benefits with respect to improving blood flow that aids the delivery of nutrients and removal of waste products from the retina, as well as beneficially altering blood chemistry."

The current study argues for a "frontline assault against the disease," Richer said, to help health professionals and patients find AMD in its earliest stages.

"Our current approach is to detect AMD at the end of the disease process and then utilize injected designer pharmaceuticals." This has helped people with advanced AMD, but there are many more people with earlier forms who have vision problems and also need help, Richer said.